By His death and resurrection, Jesus Christ has provided the means whereby every living person can have their sins forgiven and partake of eternal life. In 1 John 1:9 we are assured that "IF we confess our sins, He is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness."
Why the "if"? The Bible declares that we "all have sinned, and come short of the glory of God" (Romans 3:23). When we become convicted of this fact, we need to repent of our sins and cry to God for His mercy and pardon as David did: "Blot out my transgressions. Wash me … from mine iniquity, and cleanse me from my sin" (Psalm 51:1-4).
Only when we are thus cleansed by Him is God able to make us partakers of His life and nature. "God hath given to us eternal life, and this life is in His Son. He that hath the Son hath life; and he that hath not the Son of God hath not life. These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life" (1 John 5:11-13).